In industry, profiled workpieces are often produced on the basis of profile sections formed by extrusion of semifinished products. Depending on the material used in the semifinished product, extrusion takes place at a temperature that ensures plastic deformability. For example, aluminum or magnesium alloys are generally extruded at temperatures of 250° C. to 600° C. For further processing of the extruded profile sections, they must be cut into lengths corresponding to the respective dimensions of the profiled workpieces to be manufactured. Predominantly mechanical parting machines, such as saws or shears, are used for cutting into lengths.
Heretofore, if bent extruded profile sections are to be cut into lengths by mechanical parting means, they have had to be in cooled condition. Otherwise, because of the mechanical stress and strain during the parting process, it is not possible to rule out deformation of the profile sections and thus corresponding contour inaccuracies. Unfortunately, this prolongs the total production time, reduces the output of finished workpieces, leads to higher operating costs and ultimately makes the manufacturing process less economical.
Heretofore, it is only for straight profile sections that it has been possible, by means of “flying shears” for example, to cut extruded profile sections into lengths in the press flow while the said sections are still hot. In order to avoid a high proportion of scrap, straight profile sections are subjected to at least one further process step, in which the end contour of the profile sections are sized. Conventional straightening jigs are generally used for this purpose. If contour inaccuracies are caused by the parting means during the parting process, they are corrected by straightening. Straight profile sections are typically cut into profile-section lengths ranging from 30 to 50 meters, in order to keep the material losses small in relative terms. These losses, which are inevitable during straightening because of the need to clamp the profile-section lengths, amount to about 1 to 2 meters.
If the profile sections are subjected to plastic deformation by the action of external forces as they are discharged from the extrusion machine, or in other words if they are bent into a specified three-dimensional shape, straightening of the cut lengths of profile section is no longer feasible. If contour inaccuracies are caused while the profile sections are being cut into lengths, sizing must be performed in a technically complex contour-forming jig matched to the cut lengths of profile section. Furthermore, depending on the bend radius, in the case, for example, of profile sections bent in circular form, the lengths of the profile section must often be cut off at much shorter intervals, such as intervals of about 1 meter, in order to avoid “overrunning” of the profile section. Such relatively short lengths of profile section, however, can in general be sized only with relatively high material loss. In the case of profile sections bent after discharge from the press, therefore, it is necessary in each case to prevent contour inaccuracies caused by cutting the profile section into lengths in the press flow while the said sections are still hot.
In contrast, the object of the present invention is to provide a method of the type mentioned in the introduction, wherein the extruded profile section can be cut into lengths in the press flow while the said section is still hot, without fear that the profile section may be deformed.